Tempeh is a food made from soybeans. While not as popular in the United States as tofu, it is still a great example of how a simple food like soybeans can be woven into human food traditions in a way that is natural, inexpensive, and nourishing.
In the Health Benefits section of our Soybeansfood profile, we provide an in-depth look at many of the controversial issues surrounding soy foods and their role in health. (You may want to visit that section of our website to learn more about these issues.) One of the most important things to remember about tempeh is their basic whole food nature. The vast majority of soy consumed in the U.S. comes from a highly processed form of soy. The soybeans we consume have usually been genetically engineered, cracked, dehulled, crushed, and subjected to solvent extraction to separate their oils from the rest of the bean. What's left behind after oil extraction (defatted soy flour) is then further processed into animal feed, or processed to produce a protein concentrate or a protein isolate. The isolate can be used as an ingredient in low-fat soymilk, and the concentrate can be further processed (extruded) to form a textured soy protein for use in meat analog products (like soy burgers). Tempeh is produced with significantly less processing than most low-fat soymilks and soy burgers, and they are soy foods that are much closer to a "whole foods" category than soy protein isolates and concentrates.
While there is existing research that indicates the possibility of certain health risks from consumption of soy, we believe that a significant amount of these possible health risks involve consumption of soy in a highly processed form (like soy protein isolate or soy protein concentrate) rather than a whole food form. By contrast, we view tempeh as a form of soy that is closer to soy in its whole food form.
From a health benefits standpoint, we also like the fermented nature of tempeh. Fermentation increases the digestibility of soy (especially its proteins), nutrient absorption from soy (including absorption of phytonutrient isoflavones like genistein and daidzein), and the concentration of bioactive peptides (formed during the breakdown of soy proteins during fermentation).
According to a recent research analysis of the U.S. population and dietary practices within this population, U.S. adults would increase their intake of folate, vitamin K, calcium, magnesium, iron and fiber if we replaced our meat and dairy intake with soy, including tempeh. Replacing meat and dairy with tempeh and other soy products would also lower our total cholesterol intake by about 125 milligrams per day and our saturated fat by about 2.4 grams per day. These nutritional changes, in turn, would lower our risk of several chronic diseases, including cardiovascular diseases.
Soy foods typically contain a wide variety of well-studied phytonutrients. In the case of fermented soy foods like tempeh these phytonutrients can become more concentrated and more bioavailable as well. Below is a list of some key phytonutrients that can be found in tempeh and other soy foods.
Before concluding this phytonutrient section, we think it's important to point out one nutrient-related aspect of soy processing. Phytates are substances found in soybeans (and many other foods) that can lessen the absorption of certain nutrients, especially minerals. Soy products in general (including products that are minimally processed) contain 1.4-3.0% phytates. Soy isolates (commonly used production of low-fat soy milk) usually contain a minimum of 2.89% phytates, and soy concentrates can contain up to 4.8-4.9% phytates. Forms of soy that are more whole food-based like tempeh will do a better job of lowering your phytate exposure than highly processed forms of soy like soy protein concentrates or isolates.
We've seen very few studies of soy and cardiovascular health that are specific to tempeh. However, we do know that whole food soy products provide better cardiovascular support than dietary supplements containing isolated soy components (like purified isoflavones). We also know that fermented soy foods like tempeh have more bioactive peptides than non-fermented soy foods. (Peptides are smaller breakdown parts of proteins.) In the case of fermented soy foods, two key storage proteins—glycinin and conglycinin—are broken down by molds, yeasts, and bacteria into peptide fragments that have antioxidant, anti-inflammatory, and blood pressure-lowering properties. For example, some of the peptides found in tempeh inhibit angiotensin-converting-enzyme (ACE) and are therefore classified as "ACE inhibitors." When this enzyme is inhibited, it is often easier for the cardiovascular system to regulate blood pressure. The antioxidant and anti-inflammatory properties of soy peptides found in fermented soy foods can help protect the blood vessels from oxidative and inflammatory damage.
Intake of soy foods (especially whole soy foods) has been associated with improved levels of blood fats in numerous research studies. However, even in the case of whole soy foods, we would not describe this improvement of blood fat levels as being "strong." A better word would be "moderate." The most consistent effect of soybean intake on blood fats has been a moderate lowering of LDL cholesterol. Some studies show other positive impacts on blood fats, like the lowering of triglycerides and total cholesterol or the raising of HDL cholesterol (the "good" cholesterol). However, these additional blood fat results have not been confirmed in all studies.
Soyasaponins are soy phytonutrients that have been especially interesting to researchers with respect to their cardiovascular benefits. There is some evidence, mostly in animal studies, that soyasaponins can lessen the rate of lipid peroxidation in blood vessels, lessen absorption of cholesterol from the GI tract, and increase excretion of fecal bile acids. All of these events would be expected to contribute to a decreased risk of cardiovascular disease. Soyasaponins are provided in many forms of soy, but fermentation of soy has been shown to increase their concentration. Increased levels of soyasaponins in fermented soy foods like tempeh are likely to play a role in the better track record of fermented (versus non-fermented) soy foods in the area of cardiovascular benefits.
The area of cancer prevention is a controversial area of health research on soybeans. Many studies provide us with evidence that supports the role of whole soy foods in a cancer-preventing diet. Genistein (an isoflavone phytonutrient in soy) is often a key focus in these cancer-prevention studies. This soy isoflavone can increase activity of a tumor suppressor protein called p53. When p53 becomes more active, it can help trigger programmed cell death (apoptosis) in cancer cells, and it also help trigger cell cycle arrest (helping stop ongoing cancer cell activity). Genistein has also been shown to block the activity of protein kinases in a way that can help slow tumor formation, especially in the case of breast and prostate cancer. Importantly, genistein is found in higher concentrations in fermented soy foods like tempeh (compared to non-fermented soy foods like soymilk, isolate soy protein, concentrated soy protein, textured soy protein—also known as TVP—and non-fermented tofu).
Even in the case of fermented soy foods and their higher concentration of isoflavones like genistein, however, the potential cancer-related benefits of soy are complicated by other real-life factors. For example, the lifecycle and metabolic status of an individual seems to make a potentially important difference in the anticancer benefits of soy (even fermented soy). In studies on soy intake and breast cancer involving women who are pre-menopausal and develop tumors that are neither estrogen receptor positive nor progesterone receptor positive, soy and genistein intake (even from fermented soy foods) does not appear to offer risk reduction. Overall dietary intake may also make an important difference in the anticancer benefits of soy. For example, without strong dietary intake of fresh fruits and vegetables, even fermented soy foods may not provide reliable anticancer benefits.
In several studies, large doses of purified soy isoflavones (obtained through dietary supplements) has been associated with increased risk of certain cancers, including breast cancer. This evidence should not be surprising. Under certain metabolic circumstances, most antioxidant, anti-inflammatory, and anti-tumor compounds can also act in a way that is pro-oxidant, pro-inflammatory, and pro-tumor (often called a "proliferative" effect that is promoting of tumor growth). We view intake of tempeh as very different from intake of highly processed forms of soy, or intake of dietary supplements containing purified soy components. And our recommendations to you based on all of this information is as follows:
First, if you have a family history of hormone-related cancers like breast cancer or prostate cancer, we recommend that you consult with your healthcare provider before consuming very large amounts of soy in your diet (for example, 3 or more servings per day). And while this recommendation is a conservative one on our part, we believe that it's justified based on the current level of controversy in the health research on soy.
Second, we recommend that you choose whole food soybeans whenever possible, rather than highly processed versions like soy protein isolates and soy protein concentrates. Especially good choices in this context would be whole food-type soy products that have also been fermented, like tempeh (or fermented tofu). In general, it's worth remembering that fermented soy foods have a better track record in cancer prevention than non-fermented soy products.
Fermentation of soy foods can often result in increased formation of vitamin K, especially when bacteria called Bacillus subtilis participate in the fermentation process. When Bacillus bacteria are used to help ferment tempeh, they are able to create a form of vitamin K2 called menaquinone-7 (MK-7). Studies have shown that higher levels of MK-7 in the blood correspond to lower risk of hip fracture in older Japanese women, and that higher MK-7 also correspond to increased intake of soy foods fermented with Bacillus bacteria.
Unfortunately, however, we have not found nationally marketed tempeh in the U.S. that appears to have been fermented with the help of Bacillus bacteria as reflected in significant vitamin K content. Nutrient databases that are widely used in the U.S. to document the nutritional content of food usually report tempeh as providing no measurable amount of vitamin K in a standard serving, and since we make use of those nutrient databases in our own ranking system, we also show no measurable vitamin K in our nutrient profile for tempeh. It may be possible for you to find some tempeh products that have been traditionally fermented and that have been fermented with the help of Bacillus bacteria. If you are able to find these products, they may be able to make a valuable contribution to your vitamin K intake. However, as a general rule, it's best to assume that the tempeh you purchase at the grocery store will not be able to provide you with vitamin K.
There are several other areas of potential health benefit from tempeh that we believe deserve special mention. First is prevention and treatment of obesity. In this context, it is some of the unique peptides (protein breakdown products) in soy that have been associated with obesity prevention and treatment. Some of these peptides have shown the ability to decrease synthesis of SREBPs (sterol regulatory element binding proteins), thereby helping decrease synthesis of certain fatty acids as well as the depositing of these fatty acids in fat cells. Since fermented soy foods like tempeh have increased concentrations of bioactive peptides (versus non-fermented soy foods), tempeh may turn out to be premier forms of soy with respect to obesity management. However, it's important to remember that this fascinating research on soy and obesity is still in a very early stage.
A second area of potential health benefit is prevention of type 2 diabetes. In multiple animal studies, soy foods have been shown to lessen insulin resistance by increasing the synthesis of insulin receptors. However, this increased formation of insulin receptors only appears to occur in the presence of other dietary circumstances, like a moderate amount of polyunsaturated fat intake. High levels of total soy intake (approximately 200 grams per day) have also been associated with decreased risk of type 2 diabetes, but only in Asian populations thus far. We have yet to see specific studies on tempeh in this regard, but we look forward to more research in this area.
Other areas of active research on soy and health include chronic obstructive pulmonary disease (COPD), periodontal disease, and neurodegenerative disease. While we have yet to see studies on tempeh in these areas, we expect to learn more about potential benefits of tempeh in these areas.
Tempeh is fermented soy food that originated on the island of Java in Indonesia and is fermented with the mold Rhizopus oligosporus. Fermentation of tempeh can involve a period of several days or longer, and fermentation is usually carried out at temperatures of 85-90°F/29-32°C. Tempeh is usually purchased in a cake-like form and can be sliced in a way that is similar to tofu. However, tempeh usually has a less watery texture than tofu, and in comparison to non-fermented tofu, a more distinct flavor as well. Steaming, baking, and frying are all popular ways of preparing tempeh in many countries. Tempeh is also commonly incorporated into stews, soups, and grilled kebabs.
To understand more about tempeh's health benefits, it can be helpful to think not only about fermentation of soybeans into tempeh, but about fermentation of foods in general.
Fermentation of food typically involves the breakdown of a food's carbohydrates into gasses, alcohols, and other molecules by micro-organisms. These micro-organisms include molds, yeasts, and bacteria. Common examples of fermented food include beer and wine, cider, leavened bread, yogurt, and sauerkraut. Interestingly, a relatively small number of micro-organisms account for a very large percent of commercially fermented foods, and an even smaller number account for most fermented soy foods. Fermented soy foods (including tempeh and fermented tofu) usually involve the activity of the molds Aspergillus, Rhizopus, Mucor, Actinomucor and Neurospora; several species of the yeast Saccharomycces; and numerous species of the bacteria Bacillus and Pediococcus.
While fermentation is usually defined in terms of the action of micro-organisms on a food's carbohydrates, many nutrients in food can be transformed during the process of fermentation. These nutrients can include the food's proteins, fats. vitamins, minerals, and phytonutrients. In fermented soy foods, for example, proteins are often made more digestible through fermentation. Minerals like calcium in soy foods can become more soluble and bioavailable through fermentation as can the bioavailability of many phytonutrients, including isoflavones like genistein and daidzein. In some cases, when fermentation changes the digestibility of protein in soy foods (and in other foods as well), smaller protein fragments are created (called peptides) that have unique health supportive properties of their own. For example, one of the important storage proteins in soybeans is called conglycinin. Conglycinin and its fellow storage protein, glycinin, account for as much as 80% of the total proteins in soybeans. During the process of fermentation, conglycinin in soy is often broken down into smaller peptides that serve as antioxidants, boost immune function, and prevent excessive inflammatory response.
We believe that these whole food-based forms of soy stand in clear distinction to highly processed versions of soy like soy protein concentrate or soy protein isolate.At the same time, we also believe that the research support for the health benefits of soy foods is even stronger for fermented versus non-fermented soy foods. So we also encourage you to consider inclusion of fermented soy foods among your whole soy choices. One great option here is tempeh.
Tempeh is one of the few soy foods not originating in China, Japan, or Korea. Instead, tempeh is believed to have first been prepared on the island of Java in Indonesia, at least hundreds of years ago. However, less is known about the exact origins of tempeh than other soy foods. We do know that trade between Indonesia and China was well underway as early as 1000 AD and that soybeans may have been a part of those trading practices. We also know that a fermentation process used for coconut was already being practiced in China and that this process may have been adapted for use with soybeans. Whatever the exact origins of tempeh, it would not have been uncommon for individuals in Java, China, Japan, or Korea to think about food preparation in terms of fermentation. Fermented foods had become a well-established part of Asian cuisines for several thousand years, and it's probably most sensible to think about tempeh as a logical part of this fermented food tradition.
One resource that we encourage you to consider if you are interested in learning more about the history of soy foods, including tempeh, is the SOYINFOCENTER. This website provides several thousand pages on soy food history (and especially the history of fermented soy foods) along with research references.
For many years it was only possible to find tempeh in natural foods and Asian stores. Yet, with the growing demand for soy foods, tempeh is now becoming more and more available in supermarkets throughout the country. Depending upon the store, tempeh may either be kept in the refrigerated or freezer section.
In a well-stocked natural foods supermarket, you'll find tempeh in a variety of forms. Some of these forms are pre-cooked and ready-to eat, indicating so on the package. Other forms are not yet cooked and should be cooked before eating. You'll find plain soy tempeh that has been made from soy and Rhizopus mold but without the addition of any grains, and you will also find tempeh made from soy-grain combinations, especially soy-rice. The tempeh you find in the supermarket may also have been flavored with soy sauce or other seasonings.
Look for tempeh that is covered with a thin whitish bloom. While it may have a few black or grayish spots, it should have no evidence of pink, yellow, or blue coloration as this indicates that it has become overly fermented. In general, choose tempeh in which the soybeans and grains appear tightly bound. Also choose tempeh that tends to have a drier outside surface. High-quality, plain soy tempeh often has an aroma that would best be described as mushroom-like.
Uncooked, refrigerated tempeh can keep in the refrigerator for up to ten days. If you do not prepare the whole package of uncooked tempeh at one time, wrap it well and place it back in the refrigerator. Uncooked tempeh will also keep fresh for several months in the freezer. If you freeze tempeh and then unthaw it, you can keep the thawed tempeh in your refrigerator for about 10 days. Also, if you are purchasing tempeh from a refrigerated display in the supermarket, check the package for a "sell by" date. It should have one, and you should make sure that it's up ahead in the calendar.
GI: very low
|manganese||1.46 mg||73||5.9||very good|
|copper||0.61 mg||68||5.5||very good|
|fiber||12.00 g||48||3.9||very good|
|vitamin B2||0.40 mg||31||2.5||good|
Density>=7.6 AND DRI/DV>=10%
Density>=3.4 AND DRI/DV>=5%
Density>=1.5 AND DRI/DV>=2.5%